Manostat pump



R. D. REYMOND MANOSTAT PUMP A June 2, 1970 2 Sheets-Sheet 1 Filed May 19, 1967 i K6714 CEMENT INVENTOR [VITA 0P4 W ATTORNEYS Buns! Q REYMOND BY {Fm};- I

June 2, 1970 R. D. REYMOND MANOSTAT PUMP 2 Sheets-Sheet 2 Filed May 19, 1967 INVENTOR ATTORNEYS United States Patent O US. Cl. 128-2 3 Claims ABSTRACT OF THE DISCLOSURE A mechanical manostat pump comprises a rotary camdn'ven unit which operates conventional hypodermic syringes simultaneously and at the same rate but in opposite phase to inject fluid into and withdraw fluid from a cavity at constant presure. Conventional flexible tubing permits the desired valve action to be accomplished by a simple crimping of the tubing. To maintain constant pressure when a gas is utilized a flexible bellows type of pressure vessel is constructed with a cross-sectional area which remains constant regardless of fluid volume within the vessel as the vessel is collapsed under a constant applied force of predetermined value.

BACKGROUND OF THE INVENTION Certain medical applications and diagnostic procedures require the pumping of fluid into and out of a body cavity without causing a change in the existing cavity pressure. Examples of such requirements are:

1) The sampling of cerebrospinal fluid for bacteriological or cytological studies during which process any increase in intracranial pressures may cause herniating of the lower brain stem;

(2) Filling of the ventricles in pneumoencephalography where a pressure differential may cause ventricular distortion, stretching of the ependyma or herniating of the brain stem;

(3) Performing exchange transfusion in erythroblatosis fetalis without endangering the heart by overloading;

(4) Infusing antimetabolites in isolated areas of the body for cancer chemotherapy without overloading the local vascular system.

The problem to which this invention is directed has been recognized in the past, but heretofore, no one has introduced a device having the simplicity of construction and ease of operation of the present invention. Prior art devices have employed complicated valving and pressure compensating arrangements which are not only expensive to produce but lack in many instances the high degree of reliability offered by the present device.

SUMMARY The present invention relates to a mechanical manostat pump for the pumping of fluid into and out of a cavity without causing a change in the existing cavity pressure. A fluid source containing a replacement fluid is connected by means of a first conduit to a cavity containing a cavity fluid to be withdrawn. A cavity-filling pump is located in the first conduit for pumping the replacement fluid into the cavity. A source valve and a cavity inlet valve are provided at respective ends of the first conduit for controlling the inlet pumping operation. The cavity fluid is withdrawn by a cavity-emptying pump which is located in a second conduit which connects the cavity to a fluid receptacle. A cavity outlet valve and a receptacle valve are provided at respective ends of the second conduit for controlling the outlet pumping operation. The device is constructed'as a unit for rotary cam-driven operation with replaceable flexible tubing and conventional hypodermic syringes serving as the conduits and pumps. The valving action is accomplished by crimping the tubing to shut off the fluid flow.

The cavity-filling and cavity-emptying pumps are designed to operate simultaneously and at the same rate but in opposite phase. With both cavit valves closed and the source and the receptacle valves open, the pumps operate to draw fluid from the replacement source and empty fluid into the withdrawn fluid receptacle. When both cavity valves are opened and the source and receptacle valves closed, the pumps operate to pump replacement fluid into the cavity and withdraw cavity fluid from the cavity.

If the replacement fluid is a gas a special pressure vessel is utilized to maintain constant pressure regardless of the volume of fluid in the vessel. This is accomplished with a flexible bellows vessel having a weighted top member and a cross-section of constant area irrespective of fluid volume so that the unit pressure within the vessel remains constant.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic view of the invention illustrated in basic form;

FIG. 2 is a perspective view of a constant pressure vessel constructed in accordance with the principles of the present invention;

FIG. 3 is a top view of a preferred embodiment of the invention with a portion cut away to illustrate the operating features;

FIG. 4 is an elevation view of the device of FIG. 2 with cut-away portions to illustrate structural details; and

FIG. 5 is a cross-sectional view taken along lines '55 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction and operation of the preferred embodiment of this invention will be understood more readily by referring to FIG. 1 of the drawings which is a diagrammatic view of the invention illustrated in basic form. A cavity 1, which may be some portion of the human body, is connected to a source of replacement fluid 3 by means of tubing 5, and to a receptacle 7 for the withdrawn fluid by means of tubing 9. A cavity inlet valve 11 and a source valve 13 are located in tubing 5 for control purposes to be explained hereinafter. Similarly, a cavity outlet valve 15 and a receptacle valve 17 are located in tubing 9. Hypodermic syringes 19 and 21 are located in tubings 5 and 9, respectively. Plungers 23 and 25 of hypodermic syringes 19 and 21, respectively, are shown free from any interconnection in order to simplify the illustration, but in practice they would be interconnected in back-to-back relationship, or some mechanical equivalent, such that the plungers would be operated simultaneously and at the same rate, but in opposite directions so that fluid would be injected from one and aspirated from the other.

The system is operated by inserting needle 27 in tubing 5 between valves 11 and 13, and by inserting needle 29 in tubing 9 between valves 15 and 17. With valves 11 and 15 closed and valves 13 and 17 open, plunger 23 of hypodermic syringe 19 is withdrawn. to aspirate replacement fluid from source 3 while plunger 25 of hypodermic syringe 21 is simultaneously pushed in at the same rate to inject any fluid in syringe 21 into the receptacle 7 for the withdrawn fluid. At the end of this operation valves 13 and 17 are closed and valves 11 and 15 are opened. Plunger 23 of hypodermic syringe 19 is then pushed in to inject the replacement fluid into the cavity 1 while plunger 25 of hypodermic syringe 21 is withdrawn to aspirate fluid from the cavity 1. Valves 11 and 15 are then closed and valves 13 and 17 are opened and the process is repeated as desired.

When the replacement fluid in source 3 is a gas, it is frequently necessary to maintain this gas at a predetermined constant pressure equal to the pressure of the fluid existing in cavity 1. Under these circumstances the replacement fluid source 3 of FIG. 1 would be constructed like the constant pressure vessel shown in perspective form in FIG. 2 of the drawings. This vessel, indicated generally by the numeral 3', comprises three upstanding guide rods 33, 35 and 37 mounted in base 39 and held in spaced relation at the top thereof by means of annular ring 41. The wall 43 of the pressure vessel is made of a flexible and collapsible material, and attached to the Wall at spaced points therealong are a plurality of spacer rings, such as shown at 45, to assure accurate vertical alignment of the wall of the vessel as it collapses onto base 39. A tray 47 is provided on the top of vessel 3 to hold weights which may be placed therein. A pressure gauge 49 communicates with the interior of vessel 3 by means of tubing 51.

The desired pressure is attained within pressure vessel 3 by adding weights (not shown) to the tray 47. The design of collapsible vessel 3' is such that the force of the weights in tray 47 is applied to the fluid within the vessel via a constant cross-section area, regardless of the volume of gas within the vessel. This feature insures a constant unit pressure within vessel 3 at all times. The pressure may be monitored by means of pressure gauge 49 mounted on the side of vessel 3'.

The preferred embodiment of the invention is illustrated in FIGS. 3 to of the drawings where corresponding numerals are used to illustrate the same structural features present in the basic device of FIG. 1. The preferred embodiment of the invention utilizes the same basic tubing and hypodermic elements shown in FIG. 1, the principal difference being in a rotary cam-driven mechanism for operating the hypodermic syringes and the valve mechanism in automatic sequence. For simplicity of illustration the cavity 1, source 3 of replacement fluid and receptacle 7 for the withdrawn fluid are not shown in FIGS. 3 to 5, but it will be appreciated that they are connected to the ends of tubing 5 and 9 in the same fashion as shown in FIG. 1.

The pump of FIGS. 3 to 5 comprises a housing 5-5 having a section 57 which contains the cam-operating mechanism, and a section 59 which contains the valve mechanisms and holds in position the tubing and hypodermic syringes. Tubing 5 is held in position in section 59 by a friction fit in slots 61 and 63. Similarly, tubing 9 is held in position in slots 65 and 67. In each case the tubing enters and leaves the housing at the bottom thereof extending upwardly and forming a loop over the top of section 59, where the hypodermic needles 27 and 29 may be inserted. The hypodermic syringes 19 and 21 are mounted on the top of section 59, and are vertically offset in order to accommodate the cam structure which operates plungers 23 and 25. Plungers 23 and 25 are attached to plunger push rods 69 and 70, respectively.

Four horizontal bores 71, 73, 75 and 77 are provided in housing section 59 to accommodate the valve rods which are cam-actuated to pinch shut the tubing in proper sequence during operation. Each of the bores has a threaded end, as shown in FIG. 4, into which threaded plugs 76 and 78 may be screwed to provide a valve seat surface against which the valve tips are forced by means of biasing springs 80 and 82. The biasing springs 80 and 82 are arranged to hold valve tips 79 and 81 in constant contact with the threaded seat plugs 76 and 78 to render the valves normally closed. The cam structure to be described hereinafter pulls the valve rods against the biasing action of springs 80 and '82 to release the crimped tubing during the portion of the operating cycle when the valve is to be opened. Al-

though the valve structure has been shown only with respect to tubing 9 and horizontal bores 75 and 77, it will be appreciated that similar structure is employed in horizontal bores 71 and 73 for tubing 5.

Housing section 57 has a vertical bore 85 in which a plurality of circular cam plates are axially mounted on cam shaft 87. Cam shaft 87 may be turned in operation by the hand crank 89, as shown, or the device may alternatively be electrically driven by a suitable motive source. Handle member 91 is provided on crank 89 for hand operation.

The structure and operation of the cams will be understood from FIGS. 3 and 4 in which the top two cams are illustrated in some detail. Each of these cams comprises an upper and lower cam plate as shown at 93, 95 and 93, 95' in FIG. 4. The upper and lower cam plates have complementary cam tracks which fit over cam-follower members 97 and 99, which are mounted on the ends of the plunger push-rods 69 and 70, respectively. The configuration of the two cam tracks illustrated can be seen at 101 and 103 in FIG. 3. As cam shaft 87 is turned camfollowers 97 and 99 follow the confines of tracks 101 and 103, thereby varying in a predetermined fashion the radial distance from cam shaft 87 of follower members 97 and 99. This action causes hypodermic plungers 23 and 25 to move in andout in the desired sequence. A pair of cam plates forming a cam track of the desired configuration is provided for each of the four valves to operate each valve rod in a fashion similar to that described in connection with the plunger push rods. Proper design of the cam track configuration insures precise sequential operation of the valves and the hypodermic plungers to accomplish the action described in connection with the basic embodiment of the invention illustrated in FIG. 1.

While the invention has been shown and described with particular reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the invention.

What is claimed is:

1. A mechanical 'manostat pump for medical applications in which it is desired to pump fluid into and out of a cavity without causing a change in the existing cavity .pressure, comprising a cavity containing a cavity fluid,

a source of replacement fluid,

a receptacle for withdrawn cavity fluid,

first conduit means connecting said source to said cavity,

second conduit means connecting said cavity to said receptacle,

first and second valve means in said first conduit for controlling fluid flow therethrough,

third and fourth valve means in said second conduit for controlling fluid flow therethrough,

a first hypodermic syringe having a first plunger and a first needle, said first needle being inserted into said first conduit means between said first and second valve means,

a second hypodermic syringe having a second plunger and a second needle inserted into said second conduit means .between said third and fourth valve means,

cam means engaging said first and second plungers and said first, second, third and fourth valve means, and

means to operate said cam means,

whereby said first and second hypodermic syringes may be operated simultaneously and at the same rate to withdraw cavity fluid from the cavity and replace such fluid with replacement fluid, said valve means being operated selectively in predetermined fashion to effect such fluid transfer,

wherein said source of replacement fluid comprises a collapsible vessel of substantially constant crosssectional area, and

means to apply a predetermined constant force on the vessel such that said constant force acts on said constant cross-sectional area,

whereby a gas may be utilized as a replacement fluid without causing a change in pressures to exist.

2. The combination according to claim 1 wherein said source of replacement fluid includes a constant pressure vessel comprising vertical support means,

a flexible elongated tube member of constant cross-sectional area mounted within said vertical support means,

alignment means mounted on said tube member for holding said tube member in a predetermined alignment within said vertical support means, and

means for applying a constant force to said tube memher to act in a vertical direction and on a constant cross-sectional area of the contents of the vessel,

whereby the unit pressure within the vessel will remain constant regardless of the volume of fluid within the vessel.

3. A mechanical manostat pump for medical applications in which it is desired to pump fluid into and out of a cavity without causing a change in the existing cavity pressure comprising a cavity containing a cavity fluid,

a source of replacement fluid,

a receptacle for withdrawn cavity fluid,

a housing,

means for mounting first and second hypodermic syringes on said housing,

each syringe having a plunger and a needle,

slots in said housing for removably receiving first and second flexible tubings connecting said source to said cavity and said cavity to said receptacle, respectively,

valve rods mounted in said housing for crimping and releasing said first and second flexible tubings to control fluid flow therein,

said valve rods forming first and second valve means in said first flexible tubing and third and fourth valve means in said second flexible tubing,

the needle of said first hypodermic syringe be- 5 ing inserted in said first flexible tubing between said first ad second valves and the needle of said second hypodermic syringe being inserted in said second flexible tubing between said third and fourth valves,

and

cam means rotatably mounted in said housing and engaging said plungers of said first and second hypodermic syringes and said valve rods to operate said plungers and said valve rods in desired synchronism, whereby cavity fluid can be withdrawn from the cavity and replaced with replacement fluid.

References Cited UNITED STATES PATENTS 1,346,127 7/1920 Janes 128-214 X 1,948,388 2/ 1934 Liberson 128234 2,093,344 9/1937 Wandel 128214 2,625,932 1/ 1953 Salisbury 128214.2 2,625,933 1/1953 Salisbury 128214.2 2,646,042 7/ 1953 Hu 128-276 3,017,883 1/ 1962 Dickinson 128272 3,098,480 7/ 1963 Worthington 128-214 3,259,077 7/ 1966 Wiley et al. 128214 X FOREIGN PATENTS 1,460,715 10/1966 France.

CHARLES F. ROSENBAUM, Primary Examiner US. Cl. rX.R. 

